Investment Securities (Narrative) (Details)	3 Months Ended
	Mar. 31, 2019 USD ($) item security	Mar. 31, 2018 security	Dec. 31, 2018 USD ($) item
Investment Securities [Line Items]
Held-to-maturity securities, Number of sales	0	0
Available-for-Sale Securities, Number of sales	0	0
Restricted investment securities | $	$ 391,614,000		$ 342,712,000
Excludes U.S. Government And Its Agencies [Member]
Investment Securities [Line Items]
Number of holdings greater than 10 percent of stockholders equity | item	0		0